I had a thought....

the objective is the get it to move.

If you get the expander out the other end, and can inspect how deep the stem is in the fork,

is it possible to try using pressure instead of tension?

now Ol andy capp should come round here and look at it.

I have been in the same boat,

what if you had something that you could shove up the bottom, and clamped on top of the fork crown,
then a large shaft could push up the tube.

other idea was to use your idea to pull the stem inward, if you could get it to budge even 1 mm the battle is one


another idea- 2 pieces of wood on both sides of the stem resting on the fork crown, you would need to use hoseclamps to squeeze the 2 to the headtube-then you could apply pressure to the top of the wood

mike